Frequency Stabilization Device and Atomic Clock Device

Abstract

An electro-optic modulator that modulates a phase of laser beam with a modulation signal, an optical resonator that resonates laser beam modulated by the electro-optic modulator, and a servo circuit that adjusts a frequency of laser beam emitted by a laser device based on the optical resonator and the modulation signal are provided. The optical resonator resonates therein, laser beam at frequencies corresponding to a sideband in a frequency band of laser beam modulated by the electro-optic modulator.

What is claimed is: 
     
         1 . An atomic clock device comprising:
 a vacuum container;   an atom generator that radiates atomic beam to the vacuum container;   a first laser device that excites transition between energy levels of atoms by irradiation of the vacuum container with laser beam while the atom generator radiates atomic beam;   a detection device that detects light intensity produced in proportion to an energy transition probability of atoms generated in the vacuum container;   a controller that identifies a frequency of laser beam emitted by the first laser device based on the light intensity detected by the detection device; and   a frequency stabilization device that stabilizes the frequency of laser beam emitted by the first laser device, wherein   the frequency stabilization device includes
 a phase modulation unit that modulates a phase of laser beam with a modulation signal, 
 an optical resonance unit that resonates laser beam modulated by the phase modulation unit, and 
 a laser adjustment unit that adjusts the frequency of laser beam emitted by the first laser device, based on the optical resonance unit and the modulation signal, and 
   the optical resonance unit resonates in the optical resonance unit, laser beam at frequencies corresponding to a sideband in a frequency band of laser beam modulated by the phase modulation unit.   
     
     
         2 . The atomic clock device according to  claim 1 , wherein
 the frequency stabilization device further includes
 an oscillation unit that outputs the modulation signal, 
 an optical detection unit that detects as a detection signal, some of laser beam outputted from the optical resonance unit, and 
 a phase comparison unit that calculates a comparison value obtained by comparison between the detection signal and the modulation signal, and 
   the laser adjustment unit adjusts the frequency of laser beam emitted by the first laser device, based on the comparison value.   
     
     
         3 . The atomic clock device according to  claim 1 , wherein
 the optical resonance unit is variable in resonator length, the resonator length being variable to a length corresponding to the frequencies corresponding to the sideband.   
     
     
         4 . The atomic clock device according to  claim 1 , wherein
 the frequency stabilization device further includes a guide portion arranged between the first laser device and the phase modulation unit, the guide portion guiding some of laser beam emitted by the first laser device to the atomic clock device.   
     
     
         5 . The atomic clock device according to  claim 1 , further comprising a second laser device, wherein
 the first laser device emits first laser beam at a first wavelength, and   the second laser device emits second laser beam at a second wavelength, and   the frequency stabilization device stabilizes a frequency of each of first laser beam and second laser beam.   
     
     
         6 . The atomic clock device according to  claim 2 , wherein
 the oscillation unit outputs to the phase modulation unit, the modulation signal with which laser beam at the frequencies corresponding to the sideband can resonate in the optical resonance unit.   
     
     
         7 . The atomic clock device according to  claim 2 , wherein
 the phase comparison unit calculates the comparison value by comparing the detection signal with the modulation signal inverted in phase by 180 degrees.   
     
     
         8 . A frequency stabilization device that stabilizes a frequency of laser beam emitted by at least one laser device, the frequency stabilization device comprising:
 a phase modulation unit that modulates a phase of laser beam with a modulation signal;   an optical resonance unit that resonates laser beam modulated by the phase modulation unit; and   a laser adjustment unit that adjusts the frequency of laser beam emitted by the laser device, based on the optical resonance unit and the modulation signal, wherein   the optical resonance unit resonates in the optical resonance unit, laser beam at frequencies corresponding to a sideband in a frequency band of laser beam modulated by the phase modulation unit.